1. Field of the Invention
The present invention relates to a lubricant and to a lubricating composition.
2. Description of the Related Art
Recently, automobile regulations such as regulations regarding fuel consumption and exhaust emissions have become more and more severe. The reasons behind this are environmental problems such as global warming, air pollution, acid rain or the like, and protection of resources out of concern regarding depletion of finite petroleum energy resources. As a countermeasure, reducing fuel consumption is the most effective solution at present.
When reducing automobile fuel consumption, i.e., when improving fuel consumption, improvements in engine oil such as lowering engine oil viscosity in order to reduce engine friction loss, adding good friction regulators or the like are just as important as improvements in the automobile itself such as lightening automobile bodies, improvements in engines, etc. Although, engine oil acts as a lubricant between a piston and a liner, this is where there is a lot of hydrodynamic lubrication. Lowering engine oil viscosity can therefore decrease frictional losses. However, even though lowering engine oil viscosity has been proposed in recent years, lowering the viscosity of the lubricant causes problems such as defective sealing and increased wear. Engine oil plays an important role in lubricating valve train, bearings and the like where mixed lubrication and boundary lubrication are mostly employed. Therefore, lowering the viscosity of the engine oil causes increased wear. Friction modifiers, extreme pressure agents or the like are added thereto in order to decrease the friction loss and prevent the wear that accompanies a lowering of engine oil viscosity.
Generally, organic molybdenum compounds are added to different types of lubricant oil due to their excellent friction reducing properties. Such compounds are especially effective in engine oil for reducing fuel consumption, which makes them an essential additive for fuel consumption reducing oil. Even though fuel consumption reducing oil exhibits superior properties when new, this is not sufficient for superior fuel consumption reducing oil. Superior fuel consumption reducing oil must maintain fuel consumption reducing properties for long periods of time. Accordingly, an important characteristic for current fuel consumption reducing oil is whether the friction reducing effect can be maintained for a long period of time.
One of the organic molybdenum compounds is a molybdenum amine compound obtained by reacting an inorganic molybdenum compound such as molybdenum trioxide with a secondary amine as, for example, described in Japanese Patent Publications Nos. 5-62639, and 6-4866. In general, a secondary amine having a relatively short chain such as di(2-ethylhexyl)amine is widely used.
Through extensive research, the present inventors have discovered that a molybdenum compound having a relatively long hydrocarbon group has excellent oxidation stability and can maintain it for long periods of time upon being mixed into a lubricating base, and they have thus completed the invention.